A number of defensive vulnerabilities were exposed in Boston’s 9-3 loss to New York that underscored the degree to which the team has been destabilized in the field by the departures of Jacoby Ellsbury, Stephen Drew and Jarrod Saltalamacchia along with the injuries to Shane Victorinoand Will Middlebrooks. While starter Jon Lester was hit hard at times, the unraveling of the game was primarily the fault of the fielders behind him.

Some noteworthy instances:

A.J. Pierzynski had a passed ball in the first inning that convinced Derek Jeter to advance to second; Pieryznski’s throw was significantly off line, resulting in an error. The two-base gaffe resulted in an unearned run.

Brian Roberts grounded a single to left off the glove of a diving Xander Bogaerts in the top of the second.

Mark Teixeirablooped a double down the right field line in the top of the third on which Grady Sizemore wasn’t able to close the ground to get near the catch. On the next play, Brian McCann lined a ball to left-center on which Jonny Gomes didn’t have the range to track it down, resulting in an RBI double.

Later in the third, Sizemore got a bad break on a soft liner to right by Roberts and his attempt at a diving catch came up short, clanging off his glove for a single.

In the fifth, Mike Napoli failed to glove a liner off his glove, with the ball landing in right for a run-scoring single (with two outs). On that same play, McCann thought the ball had been caught and so started running back to the dugout. Had right fielder Sizemore realized that, he would have been able to force out McCann at second. Instead, Sizemore threw home, allowing McCann to scurry safely to second, as shortstop Xander Bogaerts held his hands on top of his head in observance of the missed opportunity for an inning-ending force. The Yankees tacked on three more runs when the next batter, Jacoby Ellsbury, rocketed a double to left-center and, after a pitching change, Derek Jeter followed with an RBI single up the middle.

The Sox’ defensive limitations played a major role in at least six runs (five of which were unearned), and also hastened Lester’s exit from the game after 4 2/3 innings and 118 pitches, resulting in more work for a bullpen that had been taxed one day earlier by Clay Buchholz lasting just 2 1/3 innings. The Sox, it is worth noting, ranked as the fourth-worst team in the majors in defensive efficiency entering the day, having converted just 68.2 percent of balls in play into outs. The limitations of the left side of their infield and their outfield corners have been felt often, and that remained true on Tuesday.

With the loss, the Red Sox are now 3 1/2 games behind the Yankees in the AL East. They’ve lost four of five so far to New York.

— Lester gave up eight runs (though just three were earned), the most he’d permitted since permitting 11 on July 22, 2012. While the Sox’ defensive betrayal was considerable (though not historic — Lefty O’Doul once saw 13 unearned runs cross the plate in a game he pitched), Lester also proved vulnerable to plenty of hard contact, as evidenced by his yield of five extra-base hits (four doubles and a triple). He also issued four walks, though he seemed displeased throughout the night with the strike zone of home plate ump Quinn Walcott.

— Sizemore’s adjustment to the outfield corners remains a work in progress, but he’s also struggling in other areas. He went 0-for-4 with a strikeout and grounding into a 4-6-3 double play on which he did not appear to be moving well down the line, and he’s now 0-for-12 dating to Friday. Over his last seven games, he’s 1-for-26 with two walks, a line of .038/.107/.038.

— In his return to Fenway, Ellsbury was a game-changing force, opening the game with a triple, later blowing the game open with a two-run double that ended Lester’s night. He also made a fantastic sliding catch on a Sizemore liner towards the gap in left-center to open the game.

— The Yankees‘ quartet of high-priced offseason additions all played huge roles for the Yankees. In addition to Ellsbury (seven years, $153 million), Masahiro Tanaka (7 years, $155 million plus a $20 million posting fee) was masterful, logging 7 1/3 innings and permitting two runs (both on solo homers) with seven punchouts and no walks while employing just 105 pitches — 13 fewer than Lester needed to record eight fewer outs. Brian McCann (five years, $85 million) went 3-for-4 with a double, two singles off the Wall and a walk. Carlos Beltran(three years, $45 million) launched a solo homer as part of a 2-for-5 game.

WHAT WENT RIGHT FOR THE RED SOX

— Mike Napoli continued his single-handed efforts to demolish the Yankees, going 2-for-4 with a screaming solo homer to left in the fourth and a double to left-center in the sixth. As a member of the Red Sox, Napoli now owns a line of .351/.429/.784 with nine homers and 14 extra-base hits against New York. He is second to Evan Longoria in homers and extra-base hits in that time. Brian McCann (five years, $85 million) was 2-for-3 with a double and a walk, and Carlos Beltran (three years, $45 million) went 2-for-5 with a homer.

— David Ortiz destroyed a 92 mph fastball from Tanaka, sending a missile that cleared the Red Sox bullpen and flew over the NESN sign on a line. The blast was likely in excess of 450 feet. However, he later was hobbled after slamming a foul ball off his right foot.

— Chris Capuano continued his brilliant work with the Red Sox, pitching 2 1/3 scoreless innings. He’s now tossed 13 shutout innings this year, and his scoreless streak now runs 13 games and 19 2/3 innings dating to last year with the Dodgers.